| 摘要 |
PURPOSE:To widen the range of stepping speed in which a magnetic head can perform seeking operation stably with no trouble of noise. CONSTITUTION:Multivibrators 2, 4 are triggered by the rising of a step signal and produce a signal 2a having pulse width t1 and a signal 4a having pulse width t3, respectively. A multivibrator 3 is triggered by the rising of trailing edge to produce a signal 3a having pulse width t2. The signals 3a, 4a are fed to an AND gate 5 which then outputs a signal 5a. A voltage control circuit 6 provides an exciting circuit 7 with an exciting voltage which is a voltage E for Low level signal 5a and a lower voltage E' for High level signal 5a. Consequently, when the stepping speed is low and the step period is longer than the pulse width t1, a step motor 8 is excited with the lower voltage E' for an interval corresponding to the pulse width t3 at the start of stepping operation and thereby the torque lowers. |
